Electric motor



1 June 14, F. w. MERRILL ELECTRIC MQTOR HUI-I:

Original Filed April 11, 1921 mm for: Hum? 14/ Mar/"W 1' rnanx w.MERRILL, or ron'r WAYNE,

' contra-NY,- moonrona'run, on NEW YORK,

Patented June 14, 1927.

UNITED STATES PATENT OFFICE.

JENDIANA, ASSIGNOR Tb WESTERN ELECTRIC N. Y., A-CORPORATION OF NEW YORK.

ELECTRIC MOTOR.

Original application m April 11, 1921, Serial No. 480,597. Divided andthis application med April 1, 1924. Serial 1%. 708,848.

This invention relates to electric motors and is a division of mycopending application, Serial No. 460,597, filed April 11, 1921. It hasparticular reference to electric motors which are designed to driveloadscontinuously and without interruption.

In its broadest aspect the invention has for its object the operationofa driven memher by means of alternative driving members which may beautomatically substituted one for the other.

One object of the invention is to so design an electric motor that itmay be shifted during full operation from one source of current toanother without decreasing its speed or mechanical output.

Another object of the invention is to so connect such a speciallydesigned motor in circuits supplied with currents of difierentcharacteristics that the motor may he switched from one source ofcurrent to the other without decreasing its speed or mechanical outputMore, specifically, the invention comprises a motor device having asingle field winding and a single armature provided with two commutatorsor two sets of slip rings, or a commutator and one set of slip rings incombination with different sources 0 current connected to each 'pair ofthese devices, and means whereby the circuits of 1 said sources ofcurrent may be alternately closed through said devices.

Still another physical embodiment of the invention comprises a singlefield winding and two electrically independent armature windings, eachprovided with a commute: tor or a-set of slip rings, a difierent sourceof current being connected to these devices, and means whereby thecircuits of said sources 055 currents may be alternately closed throughsaid devices. I

Other features of the invention not spementioned above will more clearlyappear from the following specification and accompanying drawings inwhich Fig.1 is a schematic illustration of a motor ofthe synchronoustype constructed in accordance with this invention. There is showninthis figure, circuit connections for the motor whereby it may be shiftedfrom one source of current supply to the other.

Fig. 2 is a fragmentary front elevation of a frame of automatic switchesof a telephone exchange showing a motor embodying the invention,mechanically connected thereto, for actuatin the continuous movingmechanism thereo Since synchronous motors are electric machines of wellknown design, a detailed description or illustration thereof is notthought necessary, and in Fig. 1 a synchronous motor is onlydiagrammatically illustrated. In this figure, reference numeralindicates the armature winding of the motor, the coils of which areconnected to a" Diametrically opposite d by commutator 71. points of thecommutator are connecte leads 7 2 and 73 with slip rings 74 and 75, re-

spectively. Cooperating with the commutator 71 are brushes 76 and 77carried by arms Y8 and 79 which are secured to armatures 80 and 81respectively. These armatures are adapted to be attracted by theopposite poles of an electromagnet 82. The armatures 80 and 81 arepivoted at points 83 and, when the magnet 82 is deenergized, are swungunder the influence of springs 84 so that the brushes 76 and 7! are heldin a position in which they are out of contact with the commutator 71.Cooperating with the slip rings 74 and 7 5 are brushes 85 and 86,respectively, carried by arms 87 and 88 attached to armatures 89 and 90,respective ly, of magnet 91. The armatures 89 and 90 are pivoted atpoints 92 and when the magnet 91 is deenergized the brushes 85 and 86are held in contact with. their respective slip rings by means ofsprings The control circuit hereafter to be descrihed is so arrangedthat while alternating current is heing supplied to the lorushes 85 andto drive the armature, magnets 91 and 82? are deenergized so that thesebrushes and brushes 76 and 7"? occupy the positions shown in it.However, when the source of alternating current fails, the magnets 91and 82 are energized, the energization of the former withdrawing thelorushes 85 and 86 out of contact with their associated slip 'means ofconductor 107.

rings, and the energization of the latter causing the brushes 76 and 77to be brought into contact with the commutator 71 closing the directcurrent supply, circuit for driving the armature. The operation ofmagnets 91 and 82 is simultaneous so that the the transition of currentsupply to the armature is instantaneous, causlng it to be constantlydriven from one source or the other without diminishing its speed ormechanical out ut.

e control circuit for the relays 82 and 91 together with thearrangementsof the two sources of current supply for the armature will now bedescribed. Alternating current is fed into the primary winding 94 of atransformer through a suitable type of switch 95. The secondary winding96 of the transformer has one end connected to the armature 89 byconductor 97, and its other end connected to the armature 90 by aconductor 98. In'series with conductor 98 is a winding 99 of a relay100. This relay is provided also with a.second winding 101 connected inshuntof the secondary winding 96 by a conductor 102. The relay 100 isprovided with an armature 103 cooperating with a contact 104, thearmature being connected to one side of a sourceof direct current suchas a battery 105 by conductor 106, the contact 104 being, connected inseries with the windings of magnets 91 and 82 and to the opposite sideof the battery 1.05 by The brushes 7 6 and 77 are connected to theconductors 106 and 107, respectivel ,by conductors 108 and 109. Flux 1ssupp ied the armature winding by means of a field winding 110 which isconstantly excited by current from the battery 105 through conductors111 and 112 which are connected to conductors 106 and 107.

With the switch 95 closed, the armatures of the magnets 82, 91 and relay100 will occupy theepositions shown in' Fig. 1. Alternating current isthen supplied the rotor over the following circuit: from one side of thesecondary winding 96 of the transformer, conductor 97,.armature 89,brush 85, slip rin 7 4, conductor 72, armature winding 70, con uctor 73,slip ring 75, brush 86, armature 90, series winding 99 of relay 100,conductor 98, back to the other side of the transformer 96. Flux issupplied the armature 70 by the field winding 110 which is energizedfrom batter 105, through conductors'111 and 112. T e energization of theseries winding 99 of relay 100 causes it to hold its armature in anattracted position inwhich it is out ofengagement with its associatedcontact 1043. The armature 103 is also attracted by the energization ofthe shunt coil 101 of the relay 100 through conductor 102. While thearmature 103 is in its attracted position, the circuit of the magnets 91and 82 hereafter to be described is broken so that the brushes 76, 77and 85, 86 are under control of their associated springs and held inpositions shown.

Should the switch 95 be opened or the source of alternating current suplying the primary winding 9450f the trans ormer fail,

the rotor 70 will, operate as a enerator, causing the current flowing int e circuit connecting the slip rings 74 and with the secondary winding96 of the transformer to flow in series through both coils of relay 100,whereupon the coils 99 and 101 operate differentially, permitting thearmature 103 to release and move into engagement with its associatedcontact 104, closing a circuit for the energization of magnets 91 and82. This circuit may be traced from one side of the battery 105,conductor 106, armature 103, contact 104, winding of magnet 91, windingof ma net 82, conductor 107, back to the other si e of battery 105.Relay 91 upon energizing attracts its armaturesv89 and 90, lifting thebrushes and 86 out of contact with their associated slip rings, therebybreaking. the generatin circuit connecting these slip rings with t 1esecondary winding 96 of the transformer. Magnet 82 upon energizingattracts its armatures 80 and 81 causing brushes 76 and 77 to be broughtinto contact with the commutator 71 closing an armature circuit whichmay be traced from one side of battery 105, conductor 106, conductor108, brush 77, commutator 71, brush 76, conductor 109, conductor 107,back to the other side of battery. lVith the brushes 76 and77 in contactwith commutator 71, the armature will be driven by direct currentsupplied from battery 105. Upon the closure of switch or the resum tionof the alternating current supply, the

relay winding 99 is energized, causing it to attract its armature 103,breaking the energizing circuits of the magnets 82 and 91, and restoringthe circuit conditions shown in Fig. 1.

Since magncts'82 and 91 are energized substantially simultaneously withthe deener ization of relay and are deenergized substantiallysimultaneously with the energization of the said relay 100, thetransition from" one source of current suppl fed to the armature to theother source 0 current supply fed thereto, is substantiallyinstantaneous, permitting no loss in speed of the mechanical output ofthe rotor.

Due to the fact that motors made in accordance-with this invention maybe instantaneously shifted from one source of current supply to theother without decrease in speed of mechanical output, they have a Wideapplication in power work where a constant drive is required. Such amotor, .for instance, is particularly adapted to actuate switchingapparatus of the panel type used part of such a machine switchingapparatus is illustrated in Fig. 2 and for an explana tion of thefunctions of the continuously driven rolls, reference is made to PatentNo. 1,103,623, issued July 14, 1914 to J. N. Reynolds which disclosesand describes a switching apparatus of this general type. In ordertosimplify the understanding of the mechanism shown in Fig. 2, theelements thereof have been given the same reference numerals by whichthese same parts are designated in the patent above mentioned. The threerolls 38, 38' and 38 (shown in Fig. 2) are driven through a suitablegear train (not shown) by a shaft 65 to which is mechanically connecteda motor constructed in accordance with the present invention. The

use of such a motor insures a constant actuation of the drivin shaft 65and the rolls driven thereby resu ting in a continuous power foroperating the switching elements, whereby uninterrupted telephoneservice is realized.

What is claimed is:

1. In a motor control system, a synchronous motor having a single fieldwinding and a single armature winding, slip rings and a commutatorconnected to said armature winding, one set of brushes cooperating withsaid slip rings and normally in engagement therewith, a second set ofbrushes cooperating with said commutator and normally out of engagementtherewith, separate sources of current connected to the brushescooperating with the commutator and slip rings, means for moving saidsecond set of brushes into engagement with said commutator to close one-current source therethrough upon failure of the current sourceconnected with the brushes cooperating with said slip rings, and meansfor moving the first set of brushes out of engagement with said sliprings upon failure of the current source connected thereto.

2. In a motor -control system, a synchronous motor having a single fieldwinding and a single armature winding, slip rings and a'commutatorconnected to said armature winding, one set of brushes cooperating withsaid slip rings and normall in engagement therewith, a second set oibrushes cooperating with said commutator and normally out of engagementtherewith, separate sources of current connected to the brushescooperating with the commutator and slip rings, means for moving saidsecond set of brushes into engagement with said commutator to close onecurrent source therethrough upon failure of the currentsource connectedwith the brushes cooperating with said slip rings upon the failure ofthe cur-.

rent source connected thereto, said last-mentioned means comprising arelay having two windings, one in shunt of one current source and theother in series with the brushes cooperating with said slip rings.

3. In a motor control system, a motor having a commutator and sliprings, brushes cooperating therewith, separate sources of currentconnected respectively to said commutator and to said slip rings, meansfor automatically moving the brushes cooperating with said commutatorinto engagement therewith to close the current source with saidcommutator upon failure of the current source connected to said sliprings, and means for moving the brushes out of engagement with said sliprings upon failure of the current source connected thereto.

4. In a motor control system, a synchronous motor having a single fieldwinding and a single armature winding, slip rings and a commutatorconnected to said armature winding, one set of brushes cooperating withsaid slip rings and normally in engagement therewith, a second set ofbrushes cooperating with said commutator and normally out of engagementtherewith, separate sources of current connected respectively to saidset of brushes, a magnet associated with each set of brushes, a circuitextending to said magnets, and means for closing said circuit to movethe first set of brushes cooperating with said slip rings out ofengagement therewith and to move the second set of brushes cooperatingwith said commutator "into engagement therewith.

5. In a motor control system, a synchronous motor having a single fieldwinding and a single armature Winding, sli rings and a commutatorconnected to sai armature winding, one set of brushes cooperating withsaid slip rings and normall in engagement therewith, a second set 0brushes cooperating with said commutator and normally out of engagementtherewith, separate sources of current connected respectively to saidsets of brushes, a magnet associated with each set of brushes, a circuitextending to said magnets, and a relay controlled by one of said sourcesof current for closing said circuit to move the first set of brushescooperating with said slip rings out of engagement therewith and to movethe second set of. brushes cooperating with said commutator intoengagement therewith.

6. In a motor control system, a synchronous motor having a single fieldwinding and a single armature winding, a plurality of sets of currentsupply devices connected to said armature winding, one set of brushescooperating with one set of said supply devices and normally inengagement therewith, a, second set of brushes cooperatin with a secondset of said sup 1y devices en normally out of engagement t ierewith,separate sources of current connected respectively to said sets ofbrushes, means for automatieaily moving the second set of brushes intoengagement with the set of sup 1y devices with which it cooperates uponfailure of the current source connected to the other set of brushes, andmeans for moving the first set 10 In witness whereof, I hereuntosubscribe 15 my name this 28th day of March A. D., 1924.

FRANK W. MERRILL.

